The effects of Transcranial direct current stimulation (TDCS) on the serum levels of total and phosphorylated Tau protein in patients with schizophrenia

Abstract

Schizophrenia involves cognitive deficits, including working memory impairments. Researches indicate tau protein abnormalities may contribute to cognitive dysfunction in schizophrenia. While transcranial direct current stimulation (tDCS) shows promise in improving cognitive function, its effects on tau protein and working memory in schizophrenia remain unclear. The objective of the current investigation is to ascertain the impact of transcranial electrical current-based brain stimulation on the serum concentrations of total tau protein and phosphorylated tau in individuals diagnosed with schizophrenia. Methods: In this randomized clinical trial, forty participants were randomly assigned to receive either tDCS or sham treatment. The tDCS group received anodal stimulation over the left dorsolateral prefrontal cortex (DLPFC) for 20 minutes, while the sham group received a placebo. Serum tau levels and working memory were assessed before and after using ELISA and the digit span task, respectively. Results: The results showed that the tDCS group had a significant higher increase in serum levels of phosphorylated tau protein compared to the sham group (5.53±3.67 vs. 1.49±3.90 p<0.05). There was no significant mean change difference in serum levels of total tau protein between the groups. Females displayed higher increase in both total tau (1.88 ± 0.66 vs. 1.43±0.80, p = 0.664) and p-tau levels (4.92±0.88 vs. 2.11±0.64, p = 0.014). The tDCS group also showed significantly higher improvement in working memory compared to the sham group (p<0.05). Correlations between tau changes and memory enhancements approached significance (total tau ) = 0.30; P = 0.051, r(p-tau ) = 0.27; P = 0.063).